In more than two decades of living in New York City, I am not sure I experienced a moment stranger than what happened during a Tuesday-night cab ride home from work. We were driving downtown on Fifth Avenue, past shuttered boutiques and crowds of meandering pedestrians, when, almost imperceptibly, everything went dark. At each corner, the ubiquitous streetlights and flashing walk signs winked no more. Instead, a city of shadows loomed on all sides, illuminated only by whirring police sirens and the spectral glow of red flares planted in the ground by local authorities. The sidewalks emptied out. My cab driver, who had been speaking to a friend on his Bluetooth, made a startled laugh and lifted up his phone. His reception had vanished. I checked my gadgets and found them all equally useless.

We had entered what is effectively Manhattan’s dead zone, where hundreds of thousands of residents are now in their third full day without electricity. It’s a vast swath of downtown that encompasses the city’s financial district and trendiest restaurants and is the center of New York City nightlife. It’s also where I — alongside my family and myriad friends and colleagues — live.

New York City has always been a place of haves and have-nots, carved by divides both real and imaginary. It emerged as a global metropolis not just in the rise of its gilded quarters, tony boulevards and stately townhouses but in the swarming chaos of its slums, sweatshops and teeming tenements. Daily existence here is a journey through multiple New Yorks: entrenched ethnic neighborhoods and chic bourgeois melting pots, areas worn down by poverty and marginalization and others resplendent in their power and privilege. But ever since Hurricane Sandy’s storm surge on Oct. 29 flooded a major power substation on 14th Street, there are only two New Yorks: a city of light and a city of dark.

In the first city, life after the hurricane is lurching fitfully back to normal. The power is on (in most cases, it never shut off), stores are open, the Internet is working and folk pound the streets with the city’s customary hustle and swagger. But the other city, in particular lower Manhattan, where power is expected to return by this weekend at the earliest, is an eerie ghost of itself. Candles flicker thinly from windowsills. The residents that remain walk in a hushed befuddlement. With no electricity, iffy water and scant cell-phone service, the part of town that is usually New York City’s nerve center, its pulse, is now something altogether alien and detached.

Each morning since the hurricane, I’ve woken up in lower Manhattan not to an alarm or car horns on the street but to the overwhelmingly weird silence of this alternate reality. I scrub myself clean after heating water atop a gas stove, sip from a lukewarm bottle of orange juice and then trudge down pitch-black flights of stairs with the lantern that is my dying iPhone. By the time I’ve emerged into the sunlight, I’m ready, almost, to start running away from zombies. Yet 20 minutes and a shared cab later — this new tradition itself a kind of surreal act of post-cataclysm New Yorker bonhomie — I’m in midtown, where Sandy has become, like every other natural disaster in the world, something that happened somewhere else.

Friends who would wrinkle their noses at having to go north of Union Square are now refugees in their own city, huddled masses packed into buses headed uptown. On the coastal fringes of lower Manhattan, residents from housing estates are pumping sludge water out of basements and running short of food (most shops are still closed). As the week drags on, there are fears of a full-blown public health crisis in one of the wealthiest districts in the world.

Mind you, the situation is worse for many outside of Manhattan. On Tuesday night, as I tumbled out of the cab and groped through my satchel for a flashlight, the cab driver, an immigrant from Somalia, offered to lend me his. I declined, and for good reason. His house in Bayonne, N.J., was without power and water. He has two young children at home. “Just thinking about it right now makes me want to stop, turn around and go straight to them,” he said with a sad smile. Whole stretches of Long Island, New Jersey and adjacent states will likely be without power well into next week.

The cabbie drove away, and I clattered my way up five floors to check on my mother’s apartment. A professor at New York University and an inveterate Greenwich Villager, she has so far refused to leave. Having no power is something she is accustomed to; in India, the periodic loss of electricity is a fact of life, met with a roll of the eyes, the snap of a match and the rapid filling of water basins. It’s an inconvenience, a hassle, but you live with it, like you do with traffic jams and cantankerous neighbors. I’ve tried to embrace my mother’s Zen but can’t. Slinking home beneath the eaves of Washington Square Park — the trees now monstrous black hulks — I know this won’t last. But when the city of dark gets its light back, I wonder if I’ll ever be able to see it again without its shadow.